Multiple Formats

GET("http://example.com/logo") = ...GIF data...

but... hmm... later, I find

GET("http://example.com/logo") = ...PNG data...

so I've got

GET("http://example.com/logo") != GET("http://example.com/logo")

so how about

GET : URI -> Set[Literal]

e.g.

GET("http://example.com/logo") =
	{...GIF data..., ...PNG data...}